The present invention is generally related to optical networks and, more particularly, to a system and method for mode conversion in an optical network.
Optical networks which are used for data communications and other like applications provide distinct advantages over their predecessor electrical network technologies. Chief among these advantages is a much higher rate of speed than that of electrical counterpart networks. Because of this advantage and others, such as bandwidth, optical networks are more and more being installed for local area networking applications (LANs) in office buildings, homes, and other locations as well as wide area networking applications.
With regard to the local area networking applications, often times the optical fibers employed in such environments are multimode optical fibers through which data is transmitted that originates from light emitting diodes (LEDs). While such networks provide a much faster rate of data communication than do electrical network counterparts, they are generally limited in data rate due to the data rate limitations characteristic of light emitting diodes.
In contrast, lasers have much higher data rates than light emitting diodes and have been proposed as replacements for light emitting diodes in existing optical local area networks, etc. However, the use of lasers with existing multimode optical fiber networks is problematic. Specifically, when transmitting through multimode optical fibers, lasers do not to excite all of the modes in a multimode optical fiber. This is unacceptable when, for example, passive star couplers or like devices are used for branching or distribution in the multimode optical networks. Upon encountering a star coupler, the laser radiation is often distributed among the various branches of the star coupler unevenly, which may result in the loss of signal in certain branches. In particular, this is true when the optical fiber is a graded index multimode fiber as the single-mode radiation tends to stay in the same relative modes within the multimode optical fiber.
The present invention provides a system and method for converting modes in an optical network. Briefly described, in architecture, the system comprises an optical pathway extending from an exit face of a single-mode waveguide to an entrance face of a multimode waveguide. A first ball lens and second ball lens are located in the optical pathway, with an optical link gap located between the first and second ball lenses.
The present invention can also be viewed as providing a method for converting modes in an optical network. In this regard, the method can be broadly summarized by the following steps: transmitting a laser beam along an optical pathway extending from an exit face of a single-mode waveguide to an entrance face of a multimode waveguide, and manipulating the laser beam using a first ball lens and second ball lens located in the optical pathway having an optical link gap therebetween to excite multiple modes in the multimode waveguide.
The present invention includes a significant advantage in that high speed lasers may be employed with existing multimode optical networks to increase the operating speeds of such systems. A further advantage of the present invention is that the mode converter embodiment may be constructed using an existing manufacturing platform. Other advantages of the various embodiments of the present invention is that it is simple in design, user friendly, robust, reliable, and efficient in operation, and easily implemented for mass commercial production.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein as being within the scope of the present invention.